Moore J. An overview of parasite-induced behavioral alterations – and some lessons from bats. The Journal of Experimental Biology, 2013, 216, 11-16.
“An animal with a parasite is not likely to behave like a similar animal without that parasite. This is a simple enough concept, one that is now widely recognized as true, but if we move beyond that statement, the light that it casts on behavior fades quickly: the world of parasites, hosts and behavior is shadowy, and boundaries are ill-defined. For instance, at first glance, the growing list of altered behaviors tells us very little about how those alterations happen, much less how they evolved. Some cases of parasite-induced behavioral change are truly manipulative, with the parasite standing to benefit from the changed behavior. In other cases, the altered behavior has an almost curative, if not prophylactic, effect; in those cases, the host benefits.”
Geher G. Does the flu trick people into being sociable? There’s evidence for a possible behavioral-control component of influenza. Blog posted to Psychology Today website, Jan 16, 2018.
“The more human bodies that the virus finds itself in, the more that it replicates. And from an evolutionary perspective, anything that facilitates replication should be considered as something that would have been naturally selected across evolutionary time. In short, it makes sense that the flu might manipulate people to make them interact with a higher proportion of people than usual during the communicable stage.”
Rieber C, Shattuck EC, Fiore S, Alperin P, Davis V, Moore J. Change in human social behavior in response to a common vaccine. Annals of Epidemiology, 2010, 20, 729-733.
“We carried out a prospective, longitudinal study that followed participants across a known point-source exposure to a form of influenza virus (immunizations), and compared social behavior before and after exposure using each participant as his/her own control… Results: Human social behavior does, indeed, change with exposure. Compared to the 48 hours pre-exposure, participants interacted with significantly more people, and in significantly larger groups, during the 48 hours immediately post-exposure. Conclusions: These results show that there is an immediate active behavioral response to infection before the expected onset of symptoms or sickness behavior. Although the adaptive significance of this finding awaits further investigation, we anticipate it will advance ecological and evolutionary understanding of human-pathogen interactions, and will have implications for infectious disease epidemiology and prevention.”
Rolón V, Geher G, Link J, Mackiel A. Personality correlates of COVID-19 infection proclivity: Extraversion kills. Personality and Individual Differences, 2021, 180:110994.
“The current research sought to shed light on the behavioral science that underlies the spread of SARS-CoV-2. We tested the extraversion hypothesis, which suggests that the sociability facet of extraversion may predispose people to becoming infected with the coronavirus via greater human-to-human contact… We collected data from 217 adults, aged 40 and older, from the US and the UK, of whom 53 had had the virus at some point prior to the study, and 164 had not. Participants who had had COVID-19 were more dispositionally sociable and were also more conservative-leaning compared to participants who had never had COVID-19.”
Barton MC, Bennett KV, Cook JR, Gallup GG Jr, Platek SM. Hypothesized behavioral host manipulation by SARS-CoV2/COVID-19 infection. Medical Hypotheses, 2020, 141:109750. doi: 10.1016/j.mehy.2020.109750. Epub 2020 Apr 22.
“Although not widely studied, behavioral host manipulation by various pathogens has been documented. Host manipulation is the process by which a pathogen evolves adaptations to manipulate the behavior of the host to maximize reproduction (Ro) of the pathogen. The most notable example is rabies. When a host is infected with the rabies virus it gets into the host’s central nervous system and triggers hyper aggression. The virus is also present in the rabid animal’s saliva so being bitten transmits the infection to a new host and the old host is left to eventually die if untreated. Toxoplasmosis is another example. When mice are infected they demonstrate a fearlessness toward cats, thus increasing their chances of being eaten. Toxoplasmosis needs the digestive tract of the feline to survive. Recent studies have shown that exposure to toxoplasmosis in humans (e.g., through cat feces) has also been associated with behavioral changes that are predicted to enhance the spread of the pathogen. Even the common influenza virus has been shown to selectively increase in-person sociality during the 48-hour incubation period, thus producing an obvious vector for transmission. Here we hypothesize that the novel coronavirus, SARS-CoV2, which produces the COVID-19 disease may produce similar host manipulations that maximize its transmission between humans.”
Lane N. Origin of the eukaryotic cell. Molecular Frontiers Journal, 2017, 1, 2.
“All complex life on Earth is composed of ‘eukaryotic’ cells. Eukaryotes arose just once in 4 billion years, via an endosymbiosis—bacteria entered a simple host cell, evolving into mitochondria, the ‘powerhouses’ of complex cells. Mitochondria lost most of their genes, retaining only those needed for respiration, giving eukaryotes ‘multi-bacterial’ power without the costs of maintaining thousands of complete bacterial genomes. These energy savings supported a substantial expansion in nuclear genome size, and far more protein synthesis from each gene.”